Interrogating the Dynamic Neural Computation of the Sense of Direction

项目总结/摘要 在动态环境中导航以避免危险并找到生活必需品， 保持跟踪自己的位置，并在世界中前进，这不能直接感知，而是 必须通过整合许多信息流来推断，包括前庭，本体感受和视觉。 因为定向航向有一个简单的数学定义（即，水平和方位角）， 方向感是多感觉整合和群体定量研究的沃土 编码在大脑的许多区域。 特别是，研究大脑对身体空间的表征的电生理学实验， 与环境的关系已经描述了一类被称为头部方向（HD）细胞的神经元， 当动物面向特定的优选方向时，每个都发射。这一代人的主流模式 由这些细胞编码的信号假设来自前庭的关于头部角速度的信息 系统驱动相互连接的脑干区域，背侧被盖和外侧 乳头核这些区域被建模为一个环形吸引子网络，它可以保持一个稳定的模式 由于具有相似偏好方向的神经元之间的兴奋性连接和抑制而引起的活动 有着相反偏好方向的神经元之间。然而，从前庭神经核到 含有HD细胞的脑区网络通过前置核，其主要编码 与眼睛相关的信息，而不是与头部相关的信息。因此，与眼睛相关的信息似乎在 在HD信号的生成中发挥重要作用。 头部在世界中的方向与眼睛在头部中的方向的总和定义注视方向。我们因此 假设“头部方向”网络实际上主要编码注视方向。为了 为了研究这一假设，我将从恒河猴的HD网络的多个点记录， 被动运动和主动运动使用高密度神经探针，同时跟踪眼睛， 身体和头部的运动。通过分析眼睛、头部和肢体的运动， HD系统在信息处理的多个阶段，特别是通过记录大量 同时在多个位置的神经元，该项目将提供新的见解，基本 关于大脑如何代表世界以及身体与世界的关系。

PROJECT SUMMARY / ABSTRACT Navigating dynamic environments to avoid danger and locate the necessities of life relies critically on animals keeping track of their own position and heading within the world, which cannot be sensed directly but instead must be inferred by integrating many streams of information, including vestibular, proprioceptive, and visual. Because directional heading has a straightforward mathematical definition (i.e., horizon and azimuth angles), the sense of direction represents fertile ground for quantitative study of multisensory integration and population coding in numerous areas of the brain. In particular, electrophysiological experiments studying the brain's representation of the body's spatial relationship to the environment have described a class of neurons referred to as head direction (HD) cells, which each fire when an animal is facing a specific preferred direction. The prevailing model for the generation of the signal encoded by these cells assumes that information about angular head velocity from the vestibular system drives activity changes in reciprocally-connected brainstem areas, the dorsal tegmental and lateral mammillary nuclei. These areas are modeled as a ring attractor network, which can maintain a stable pattern of activity due to excitatory connections between neurons with similar preferred directions and inhibition between neurons with opposing preferred directions. However, the main projection from the vestibular nuclei to the network of brain areas containing HD cells is via the nucleus prepositus, which principally encodes eye-related rather than head-related information. Thus, it seems likely that eye-related information plays a substantial role in the generation of the HD signal. The summation of head-in-world direction with eye-in-head direction defines gaze direction. We thus hypothesize that the "head direction" network in actuality primarily encodes gaze direction. In order to investigate this hypothesis, I will record from multiple points of the HD network in rhesus macaques during both passive motion and active locomotion using high-density neural probes while simultaneously tracking eye, body, and head movements. By analyzing eye, head, and limb movements in conjunction with recordings from the HD system at multiple stages of information processing, and in particular by recording from large numbers of neurons at multiple locations simultaneously, this project will provide new insights into fundamental questions about how the brain represents the world and the body's relationship to it.